Cylinder head gasket

ABSTRACT

Cylinder head gasket for sealing the sealing gap between engine block and cylinder head of a multi-cylinder internal combustion engine comprising a sealing plate with several combustion chamber orifices, combustion chamber sealing elements at the edges of the sealing plate which surround the combustion chamber orifices and a sensor element for detecting sealing gap movements, wherein for the cylinder-specific detection of the sealing gap movements perpendicular to the plane of the sealing plate which are caused by the pressure changes in the respective combustion chamber, the sealing plate is provided with several sensor elements associated with the combustion chamber orifices, the sensor elements are arranged outside of the combustion chamber sealing elements and the sensor elements belong to the following group: piezoelectric, piezoresistive and capacitive sensors as well as glass fiber light guide sensors with transmission loss which is changeable by bending the light guide axis.

The invention relates to a cylinder head gasket for sealing the sealinggap between the engine block and the cylinder head of a multi-cylinderinternal combustion engine comprising a sealing plate with severalcombustion chamber orifices, combustion chamber sealing elements at theedges of the sealing plate which surround the combustion chamberorifices and a sensor element for detecting sealing gap movements.

When hereinabove and hereinbelow reference is made to combustion chambersealing elements, so-called combustion chamber borders are also to beunderstood by these, i.e., ring-shaped sheet metal elements of L- orC-shaped cross section which border the edges of the sealing platesurrounding the combustion chamber orifices.

Electronic means are used increasingly for the controlling, regulatingand monitoring of reciprocating internal combustion engines. Owing tothe use of less and less expensive microprocessors, the total cost ofthe control and/or regulating and/or monitoring circuits is essentiallydetermined by the cost of the sensors. As the cylinder head gasket isdirectly exposed to the influence of the combustion process in areciprocating internal combustion engine, it is the ideal location forplacing sensors for determining the operating parameters of the internalcombustion engine for the use of sensors designed as separate componentsoften fails for cost and space reasons as is, for example, the case withthe restricted installation possibilities in a 4-valve engine.

There is known from DE-OS 2 917 406 (FIG. 1 in conjunction with claims 1and 2) a cylinder head gasket with a sensor integrated in the sealingplate for detecting the oscillations which occur with knockingcombustion. The actual sensor is in the form of an electric resistancesection consisting of carbon powder and is arranged in a cavity locatedinside the soft material essentially forming the sealing plate in theimmediate vicinity of a cylinder head screw. The sensor thus operatesaccording to the principle of the known carbon microphone and registersthe pressure which prevails at its location in the sealing gap andchanges with respect to time.

Purposeful monitoring and/or control and/or regulation of the enginewhich is capable of meeting today's requirements should, however, enablecylinder-selective detection of the operating parameters so that, forexample, the combustion process can be separately monitored for eachindividual cylinder--it is quite possible that knocking combustion willoccur in one of the cylinders but not in the other cylinders (owing to,for example, the different cooling conditions of the cylinders anddeposits in the combustion chambers). The same applies to so-calledmisfirings as a result of, for example, failure of a spark plug, topre-ignitions, to retarded combustion or to the changing of theinjection behavior in diesel engines. It has, however, been shown thatcylinder-selective detection of certain operating data is not possiblewith the sensor means known from DE-OS 2 917 406.

There is known from DE-OS 3 006 603 a cylinder head gasket withtemperature sensors integrated in its sealing plate. The purpose of thetemperature sensors is to detect a knocking combustion process. Thisprior art discloses two basically different variants: In a first groupof embodiments of the known cylinder head gasket (see FIGS. 2, 3, 5 to 7and 9) the sealing plate has a combustion chamber border for eachcombustion chamber orifice, and the temperature sensors are arrangedwithin these combustion chamber borders. If on account of the inabilityof a temperature sensor to detect a knocking combustion process whichdoes not occur constantly, the temperature sensors in this knowncylinder head gasket were replaced by sensors suitable for detectingsealing gap movements, these would be exposed to much too hightemperatures because of their arrangement within the combustion chamberborder. Furthermore, such a solution could not be implemented at leastwith the present state of the art for space reasons, and, finally, thesealing gap oscillations would only be detected by the flange surfacesof the combustion chamber borders of approximately C-shaped crosssection, which would result in sensor signals which are too indefinite.Any integration of a sensor in a combustion chamber border also resultsin inhomogeneity of the combustion chamber border and hence in a localweak spot which endangers the reliability of the combustion chambersealing. In the variant shown in FIG. 1 of DE-OS 3 006 603, the sealingplate has neither a combustion chamber border nor a combustion chambersealing element at the combustion chamber orifices. A temperature sensorarranged directly at the edge of the respective combustion chamberorifice would, however, lie within a combustion chamber border if thiscombustion chamber orifice were provided with such a combustion chamberborder, which would have the consequences explained hereinabove.

DE-OS 3 001 711 discloses a cylinder head gasket with light guidesarranged on its sealing plate. These terminate in openings of combustionchamber borders and hence at the combustion chambers in order to detectfluctuations in brightness which are caused by the strong gasoscillations which occur during a knocking combustion process (see FIG.5 in conjunction with FIG. 4). Therefore, in this known cylinder headgasket, a light guide represents a pure optical system and does notconstitute a sensor. This known cylinder head gasket also has thedisadvantage of having unavoidable weak spots in combustion chamberborders or sealing elements through which the light guides have to beled.

The object underlying the invention was to enable in a multi-cylinderinternal combustion engine cylinder-selective detection of thecombustion process with less expenditure than in known constructionswhich operate, for example, with sensors integrated in the spark plugsor with sensors designed as separate components and mounted in thecylinder head.

To accomplish this object, one resorts, in accordance with theinvention, to a cylinder head gasket of the kind mentioned at thebeginning, as known, for example, from DE-OS 2 917 406 but which isdesigned, in accordance with the invention, such that its sealing plateis provided with several sensor elements associated with the combustionchamber orifices for the cylinder-specific detection of the sealing gapmovements perpendicular to the plane of the sealing plate which arecaused by the pressure changes in the respective combustion chamber,that, furthermore, the sensor elements are arranged outside of thecombustion chamber sealing elements, and that, finally, the sensorelements belong to the following group: Piezoelectric, piezoresistiveand capacitive sensors as well as glass fiber light guide sensors withtransmission loss changeable by bending the light guide axis. Suchsensors are characterized, above all, by the following advantages: Theyare sufficiently resistant to the temperatures and vibrations to whichthey are exposed in a cylinder head gasket during engine operation, theycan be constructed sufficiently small and are available at low cost and,above all, the piezoelectric and the above-mentioned glass fiber lightguide sensors ensure such a high signal level that electromagneticinterference factors are of no great importance. Owing to thearrangement of the sensor elements outside of the combustion chambersealing elements, the disadvantage mentioned hereinabove in thediscussion of known cylinder head gaskets do not occur. Furthermore, theinertialess response of the sensor elements to be used in accordancewith the invention is to be emphasized, an advantage which thetemperature sensors of the known cylinder head gaskets according to thepreviously discussed DE-OS 3 006 603 do not have. Owing to theintegration of several sensor elements in the cylinder head gasket,preferably at locations of the sealing plate which are immediatelyadjacent to the combustion chamber orifices, the combustion processes inthe various cylinders can be reliably detected in a cylinder-selectivemanner because the sealing gap oscillations perpendicular to the planeof the sealing plate which are caused by the combustion pressure aredetected for each cylinder and signals are obtained which enablemonitoring and control and regulation of the combustion process. Herein,no elaborate structural measures are necessary on the engine components(engine block and cylinder head), as is the case in the prior art, whenthe combustion process is detected in a cylinder-selective manner.Moreover, owing to the arrangement of the sensor elements outside of thecombustion chamber sealing elements, reliable combustion chamber sealingwhich is always difficult to implement is not endangered.

Use of an inventive cylinder head gasket enables not only continuousmonitoring of the engine but, in particular, early recognition of enginedefects such as, for example, misfirings, over the entire operatingrange; therefore, countermeasures can already be taken before the totalfailure of an important component so that, for example, the fuel supplyto a cylinder can be cut off when a spark plug has failed several times.Precisely this possibility of early recognition of crawling defects suchas, for example, leakage of the induction system or failure of aninjection valve, is a special advantage achievable with an inventivecylinder head gasket as such defects have hitherto only been detectedupon total failure of the respective component. This represents aconsiderable advance as currently only an exhaust gas test on thedynamometer allows definite checking of a vehicle engine, i.e., theprior art offers only an indirect measuring method, but no continuouslyoperating measuring system fixed on the vehicle. Also the sensorelements of an inventive cylinder head gasket provide a definite signalas regards knocking combustion for each cylinder, which enables savingof the hitherto used, separate knock sensors--the conventional knocksensors detect the high-frequency oscillations (approximately 7 kHz)caused by the sudden combustion of the mixture far away from the placeof origin, whereas with use of an inventive cylinder head gasket, theoscillations are detected in the immediate vicinity of the place oforigin, i.e., the sensor elements deliver a specific signal for theknocking combustion without strong, superimposed interferences, forexample, in the form of oscillations caused by piston slap or by thevalve drive, interferences which in the prior art always requireelectronic processing of the signal provided by the knock sensor withthe use of window functions and filters. Hence the inventive cylinderhead gasket enables simplification of the signal processing and providesmore definite signals, and particularly in view of the knocking of anengine, the inventive cylinder head gasket represents a great advanceowing to the obtaining of cylinder-specific signals because, asmentioned previously, the knocking sensitivity of the various cylindersof a multi-cylinder internal combustion engine can differ to quite anextent.

Furthermore, with use of an inventive cylinder head gasket,pre-ignitions (inflaming of the mixture by locally limited, hot pointsin the combustion chamber prior to the desired point of ignition) can beimmediately recognized so that appropriate countermeasures can beintroduced at once by the electronic engine managing system. Sincechanges in the sealing gap between engine block and cylinder head orchanges in the thickness of the sealing plate of the cylinder headgasket are caused by the combustion process, the invention makes itpossible for the phase position of the combustion process relative tothe rotational angle position of the crankshaft to be directly detectedin a continuous and cylinder-specific manner so that the known enginecontrol systems can be extended to a control circuit. In this way anoptimum point of ignition can be ensured for all operating conditions,for example, also for unstable engine operation. Furthermore, theregulation of the combustion process represents an aid in reliablycontrolling the so-called lean operation of an internal combustionengine with air conditions of more than 1.6. Evaluation of the signalsof the sensor elements of an inventive cylinder head gasket with respectto the pressure gradient (pressure rise in the combustion chamber perdegree of rotational angle of crankshaft) also offers the possibility ofoptimizing the combustion process with respect to lower sound emission.Owing to the increasing traffic density and today's demands for comfort,the idling behavior of an internal combustion engine is becomingincreasingly important, more specifically, with respect to exhaust gasemission, fuel consumption and idling quality (noise development,disturbing misfirings, noticeable vibrations of the vehicle). However,known special regulating devices for controlling the idling speed onlyintervene when the combustion process is already terminated--here theinvention with its direct monitoring of the combustion process offersmuch better possibilities for intervening.

In principle, the sensor elements of an inventive cylinder head gasketcan be arranged anywhere on or in the sealing plate if their spatialrelation to the combustion chamber orifices is such that they generatesufficiently cylinder-selective signals. Also a separate sensor elementdoes not have to be provided for each combustion chamber orifice; it is,for example, possible to arrange the sensor elements in the gussets ofthe sealing plate between the combustion chamber orifices so that eachsensor element is at the same spacing from two adjacent combustionchamber orifices--it is then only necessary to separate the specificsignals generated by a certain sensor element for the two adjacentcombustion chambers in an electronic evaluating system and allocatethese clearly to the two combustion chambers, which is unproblematicinsofar as every present-day engine is equipped with a rotational anglesensor coupled with the crankshaft anyhow so that the signals generatedby this sensor element can be readily specifically allocated to the twoadjacent combustion chambers in the electronic evaluating system bymeans of window functions. However, embodiments of the inventivecylinder head gasket are preferred in which at least one sensor elementis provided for each combustion chamber orifice.

Finally, it should be pointed out that the behavior of the combustionchamber pressure does not have to be detected as an absolute value bythe sensors of an inventive cylinder head gasket, but only a signal hasto be generated to enable determination of that rotational angleposition of the crankshaft at which the maximum combustion chamberpressure occurs in the associated cylinder. Therefore, only a relativemeasurement with subsequent, simple peak value determination isnecessary and so ageing of the sensor elements is not critical.

In a cylinder head gasket whose sealing plate is approximatelyrectangular with screw holes for cylinder head screws approximatelyalong lines extending parallel to its longitudinal edges and web-likeregions between its combustion chamber orifices, the screw holes beingarranged approximately in the extensions of these web-like regions, itis recommendable to provide at least one sensor element for eachcombustion chamber orifice and to arrange the sensor elements in theregions between the screw holes. This preferred embodiment is based onthe following recognition: As changes in the sealing gap or changes inthe thickness of the sealing plate of the cylinder head gasket arecaused by the combustion process and these changes are greatestapproximately at the center between the cylinder head screws owing tothe engine component elasticities, such an inventive cylinder headgasket results not only in cylinder-specific signals but also in signalswhich are particularly easy to process on account of the low noisecomponent; this applies particularly when sensor elements extending overa small area are arranged at the center between the cylinder headscrews.

From ATZ 70, (1968) 6, page 211, picture 5, it is known to detect thesealing gap oscillations between two cylinder head screws, but thisprior art shows a construction which is not at all comparable with theinventive cylinder head gasket for the following reasons: In the knownconstruction, the housing of an inductive displacement sensor is fixedlyconnected to the top surface of a cylinder head base plate, and apin-shaped feeler which actuates the inductive displacement sensorengages through the cylinder head base plate and the sealing plate ofthe cylinder head gasket and rests against the top surface of the engineblock. The feeler extends through a hole in the cylinder head sealingplate which penetrates the combustion chamber border and thereby weakensit. Moreover, this known device does not measure the movements of thecylinder head underside with respect to the engine block side exactly onaccount of the attachment of the housing of the inductive displacementsensor to the top surface of the cylinder head base plate. Finally, thegeometrical size and the acceleration sensitivity to engine oscillationslead to additional problems, and elaborate sealing of the feeler pinfrom the cooling water area is necessary. If the teaching from ATZ 70(1968) 6, page 211, picture 5 were transferred to the cylinder headgasket of DE-0S 2 917 406, the sensor integrated in the sealing platewould have to be arranged between the flanges of the combustion chamberborders of C-shaped cross section, which would produce the disadvantagespreviously explained hereinabove.

If it is assumed that sensor elements which have a constant activesurface are used in an inventive cylinder head gasket, suitable sensorelements made available by the prior art detect either the change indisplacement of the surfaces of engine block and cylinder headdelimiting the sealing gap or the change in the surface pressure actingon the cylinder head gasket or (in the case of a constant sensorsurface) the change in the force acting on the respective sensorelement. Passive or active detectors can be used for the sensor elementswhich are to be integrated in accordance with the invention in thecylinder head gasket; examples of passive detectors are piezoresistivesensor elements and the above-mentioned glass fiber light guide sensorsbut also capacitive sensors; examples of active detectors arepiezoelectric sensor elements such as piezoelectric ceramic discs orpiezoelectric foils.

The sensor elements of inventive cylinder head gaskets can be formed bydiscrete components; here piezoelectric ceramic discs are preferred.Alternatively, the sensor elements can, however, also be formed bysensitive areas of an elongate sensor which runs past all combustionchamber orifices; such an embodiment can be realized in two differentways: Either the elongate sensor has inactive areas between itssensitive areas associated with the various combustion chamber orificesor the elongate sensor is sensitive over its entire length and thesignals generated by its sensitive areas associated with the variouscombustion chamber orifices are, as mentioned previously hereinabove,divided up by an electronic evaluating system, for example, with theassistance of window functions and clearly allocated to the variouscylinders. In the last-mentioned case, one requires only a single signaltap at the elongate sensor. Division of the elongate sensor intosensitive areas associated with the individual combustion chamberorifices and into inactive areas can be implemented in different ways:The elongate sensor can be placed on or in the sealing plate, forexample, such that the sensor sections forming the sensitive areas lieclose to the combustion chamber orifices and the remaining sensorsections lie in areas of the cylinder head gasket which are not pressedwhen the cylinder head gasket is mounted. It is, however, also possibleto place the sensor sections forming the inactive areas, for example, instiff tubes or the like so that they are not pressed or exposed toalternating pressures or deformations.

Optimum signals are obtained when in an inventive cylinder head gasketthe sensor elements are arranged as close as possible (even if, forexample, cooling water ports lie between the sensor elements and thecombustion chamber orifices) to the adjacent combustion chamber sealingelements, but not in the area of the actual combustion chamber sealingelements--temperatures which are still intolerably high for the sensorelements may prevail there, and the geometrical relations would make theconfiguration and arrangement of the sensor elements considerably moredifficult.

If the sensor elements or sensors of inventive cylinder head gaskets areglass fiber light guide sensors with transmission loss changeable bybending the light guide axis, the ends of such a light guide have, ofcourse, to be provided or coupled with a light emitter and a lightreceiver; these elements can, however, be readily arranged outside ofthe areas exposed to high temperatures and strong vibrations.

The subject matter of the invention is, furthermore, the use of aninventive cylinder head gasket in a reciprocating internal combustionengine comprising a control and/or regulating and/or monitoring circuit,wherein, in accordance with the invention, the sensor elements of thecylinder head gasket are components of this circuit. In particular, thesensor elements are used to recognize misfirings and, in the givencircumstances, to cut off the fuel supply to the corresponding cylinderand/or as knock sensors and, in the given circumstances, to change thepoint of ignition of the respectively associated cylinder. It may alsoprove expedient to arrange a further part of the circuit on the sealingplate apart from the sensor elements, more specifically, on an edge areaof the sealing plate which is exposed when the cylinder head gasket ismounted; this circuit part is, in particular, a preamplifier forimproving the quality of the signals generated by the sensor elements.

Further features, advantages and details of the invention are also to befound in the following description and the appended drawings of severalpreferred embodiments of the inventive cylinder head gasket; thedrawings show:

FIG. 1 a plan view of a first embodiment of the inventive cylinder headgasket for a four-cylinder engine, but it should be noted that thenumber of cylinders could be different;

FIG. 2 a section through this cylinder head gasket along line 2--2 inFIG. 1;

FIGS. 3a and 3B two diagrams in which the signals generated by apiezoelectric sensor element of an inventive cylinder head gasket areplotted against the rotational angle position of the crankshaft, withFIG. 3a showing the signal curve in the case of ignition in the cylinderassociated with the sensor element and FIG. 3b the signal curve withoutignition in this cylinder;

FIG. 4 a section corresponding to FIG. 2 through a second embodiment ofthe inventive cylinder head gasket;

FIG. 5 a section through a further embodiment of a sensor element for aninventive cylinder head gasket, with the section corresponding to thesectional illustrations in FIGS. 2 and 4;

FIG. 6 a highly simplified plan view of a further embodiment of theinventive cylinder head gasket which in contrast with the embodimentshown in FIG. 1 does not have several discrete sensor elements butinstead an elongate sensor common to all combustion chamber orificeswhich is connected to a schematically represented electronic evaluatingsystem;

FIG. 7 a section through this cylinder head gasket along line 7--7 inFIG. 6;

FIG. 8 a section through part of a further embodiment of the inventivecylinder head gasket, with the section being taken on line 8--8 in FIG.6; and

FIG. 9 a schematic plan view of a partial area of a further embodimentof the inventive cylinder head gasket.

FIG. 1 shows a cylinder head gasket 10 with a sealing plate 12 havingfour combustion chamber orifices 14, 16, 18 and 20, with the edgeregions of the sealing plate 12 surrounding the combustion chamberorifices being bordered with so-called combustion chamber borders 22.These combustion chamber borders are ring-shaped sheet metal elements ofC-shaped cross section which engage over the edges of the sealing plate12. Instead of such combustion chamber borders, any other combustionchamber sealing elements of a known kind can, of course, also be used.Between the combustion chamber orifices 16 and. 18, the combustionchamber borders 22 were partly broken away to illustrate that thesealing plate 12 forms between the combustion chamber orifices webs 24in the extension of which the gasket 10 is provided with screw holes 26for cylinder head screws. Two further screw holes 26 are located in eachcase beside the terminal combustion chamber orifices and the narrowsides of the sealing plate.

In the region of its one longitudinal side, the sealing plate 12 isprovided in accordance with the invention with a web-like projection 30;when the cylinder head gasket is mounted in the engine, all of theregions of the sealing plate 12 are covered throughout their entiresurface by the cylinder head and the engine block with the exception ofthis projection 30 which protrudes at the side beyond the engine blockand the cylinder head.

FIG. 1 shows a plan view of the cylinder head gasket, more specifically,viewed from the side of the engine block. On account of the lowercomponent temperature, there is preferably attached, in particularadhesively, to this side of the sealing plate a sensor unit 32 which, aswill be explained with reference to FIG. 2, consists of two sheets,sensor elements arranged between these, electric connection lines andcontact elements.

As shown in FIG. 1, there is located between two screw holes 26 andbetween the associated combustion chamber orifice, on the one hand, andthe top longitudinal edge of the sealing plate 12 according to FIG. 1,on the other hand, in each case, a sensor element 34, 36, 38, 40 which,as shown in FIG. 2, has the shape of a small flat plate with twoconnection lines 34a, 34b; 36a, 36b, etc., connected to it in eachrespective case. The sensor elements and the connection lines liebetween two sheets 42 and 44 whose shape corresponds in the plan view tothat of the entire sensor unit 32 and whose edges are intimately joined,in particular by welding or adhesion, as indicated in FIG. 2. On theface of the sheet 42 facing outwards there are eight plate-shapedmetallic contact elements 46¹ to 46⁸ arranged alongside one another in arow on the projection 30, with the connection line 34a leading to thecontact element 46¹, the connection line 34b to the contact element 46²,the connection line 36a to the contact element 46³, the connection line36b to the contact element 46⁴, the connection line 38a to the contactelement 46⁵, the connection line 38b to the contact element 46⁶, theconnection line 40a to the contact element 46⁷ and the connection line40b to the contact element 46⁸. When the inventive cylinder head gasketis connected to a control and/or regulating and/or monitoring circuit,the contact elements 46², 46⁴, 46⁶ and 46⁸ are connected to one anotherand to ground whereas at the contact elements 46¹, 46³, 46⁵ and 46⁷signals can be picked up which are specific for cylinder I, cylinder II,cylinder III and cylinder IV, respectively, which correspond to thecombustion chamber orifices 14, 16, 18 and 20. 0n account of theprojection 30 of the inventive cylinder head gasket and the contactelements 46¹ to 46⁸ arranged on it, these signals can be picked upsimply with a multipole plug connector 70 which can be attached to theprojection 30 of the cylinder head gasket. The plug connector can alsobe electrically wired. Furthermore, it is possible to connect theconnection lines directly to an electronic amplifier (for example, thickfilm circuit) which is arranged between the foils 42 and 44 or on thetop surface of the foil 42 in the region of the projection 30.

As the sensor elements are advantageously arranged on the side of thecylinder head gasket facing the engine block, the sealing plate 12 hasindentations 50 (see FIG. 2) on this side, more specifically, either asingle indentation stepped depth-wise for the entire sensor unit 32or--owing to the small thickness of the sheets 42 and 44 and of theconnection lines--a separate indentation for each of the sensorelements.

The cylinder head gasket illustrated in the appended drawings is one inwhich its sealing plate consists of a metal carrier plate 62 which iscoated on both sides with so-called soft material 60 and from whichanchoring tongues 64 are bent outwards on both sides to anchor thelayers of soft material to the metal carrier plate. 0f course, theseanchoring tongues must be of such dimensions or deformed in such amanner by stamping that there is no danger of the sensor unit 32 beingdamaged by the anchoring tongues when the cylinder head is tightened.The sensor unit can, however, also be used in conjunction with cylinderhead gaskets of a different design, for example, with a sealing plateconsisting of single- or multi-layer sheet metal.

In the drawings, the connection lines were drawn so as to runessentially in a straight line. However, this was done merely tosimplify the illustration for in the preferred embodiment of theinventive cylinder head gasket the connection lines should have ameandering course and, in particular, take the form of conductor trackswhich are printed on the sheets and are then conductively connected tothe contact elements 46¹ to 46⁸ through the foils.

The remaining components of the cylinder head gasket shown in FIG. 1were not described as these do not relate to the present invention. Alsonot illustrated was the control and/or regulating and/or monitoringcircuit to which the sensor unit 32 is connected. Only part of a plugconnector 70 which can be pushed onto the projection 30 to electricallyconductively connect the contact elements with the above-mentionedcircuit was indicated in FIG. 1.

In accordance with the invention, the sensor elements 34 and 40 couldalso be arranged between the terminal screw holes 26; it is, however,also conceivable to arrange two additional sensor elements between theseterminal screw holes 26.

In accordance with a further feature of the invention, the sensorelements are advantageously arranged on that longitudinal side of thesealing plate which is located opposite the exhaust manifold side of theengine in order to keep the temperature load on the sensor elements aslow as possible.

Finally, it is also to be seen as lying within the scope of theinvention to arrange only a single sensor element at one of thelocations designated hereinabove. Its signal is then used forcontrolling and regulating concepts of all of the cylinders; one thenproceeds from the simplification that all of the cylinders behaveidentically.

In the explanation of FIG. 3 (FIGS. 3a and 3b) it is assumed that thetwo diagrams show the, in the given circumstances, amplified outputsignal of the sensor element 34 which is allocated to the combustionchamber orifice 14 for the first cylinder (cylinder I). The outputsignal of a piezoelectric sensor element was recorded, morespecifically, the signal amplitude A was plotted as ordinate against therotational angle (abscissa) of the crankshaft. Those crankshaftpositions in which the piston of cylinder I and the piston of cylinderII belonging to the combustion chamber orifice 16 are at the upper deadcenter where designated OT-I and OT-II, respectively. As mentionedpreviously, FIG. 3a shows the output signal of the sensor element 34allocated to cylinder I during normal engine operation, i.e., withignition of the mixture in cylinders I and II, whereas FIG. 3b shows theoutput signal of the sensor element 34 allocated to cylinder I after thespark plug connector for cylinder I was removed--i.e., the mixture incylinder II was ignited in a normal way. In accordance with thecombustion process, the output signal A illustrated in FIG. 3a has anextreme value 80 after the upper dead center OT-I of the piston ofcylinder I, whereas a following, considerably lower extreme value 82 ofthe output signal A is due to the change in the sealing gap at thelocation of the sensor element 34 allocated to cylinder I which wascaused by the combustion process in the neighboring cylinder II.

The output signal B of the sensor element 34 illustrated in FIG. 3bshows a first extreme value 80' which is not only substantially smallerthan the first extreme value 80 of the output signal A but also liesprecisely at the upper dead center OT-I of the piston of cylinder I. Thereduction in size and shift of the first extreme value 80' of the outputsignal B in comparison with the first extreme value 80 of the outputsignal A are due to the flatter pressure gradient without an ignitionprocess (polytropic compression) in cylinder I, whereas the secondextreme value 82 of the output signal B corresponds, as is to beexpected, with respect to size and phase position to the second extremevalue 82 of the output signal A because an ignition process also tookplace in cylinder II when the output signal B was recorded.

Hence comparison of FIGS. 3a and 3b shows that the sensor element 34clearly indicates a misfiring or combustion failure in cylinder I, morespecifically, both by displacement of the signal maximum or extremevalue 80' to the upper dead center OT-I of cylinder I and by a veryclear reduction in size of the signal maximum or extreme signal valuecompared with the signal maximum or extreme signal value obtained whenignition took place.

For reasons of completion, it should be noted that FIGS. 3a and 3billustrate the output signals A and B in smoothed form for in realitythe illustrated useful signals are superimposed by high-frequencyinterference signals whose amplitudes, however, are only a fraction ofthe amplitudes of the useful signals.

FIG. 4 shows a particularly preferred embodiment of a sensor elementintegrated in a cylinder head gasket. This consists of a smallpiezoelectric ceramic disc 84 which is welded in between plastic sheets86 and 88. The plastic sheets 86, 88 are preferably--as in theembodiment according to FIGS. 1 and 2--strips of sheet between which theceramic discs 84 are arranged for all combustion chamber orifices of thecylinder head gasket.

A polyimide sheet is preferably used as it is resistant to temperaturesof up to approximately 400° C. and can be laminated, metal-coated,stamped, cut and coated with adhesive. Between the plastic sheets 86 and88 and the ceramic disc 84 there extend metallic conductor tracks 90 and92 which are preferably conductor tracks which are printed or mounted insome other way on the plastic sheets and by means of which the ceramicdisc 84 is contacted on its two opposite main surfaces to enable theelectric signal generated by the piezoelectric ceramic disc when actedupon by pressure to be picked up. The sensor element designated in itsentirety 94 is arranged in an opening 96 which, in particular, isstamped out of a sealing plate 98 of the cylinder head gasket, morespecifically, such that the top main surface 100 of the sensor element94 is flush with the top main surface 102 of the sealing plate 98. Theregion of the opening 96 located below the sensor element 94 is filledout with a relatively hard elastomeric material 104 so that when thecylinder head gasket is mounted between cylinder head and engine block,the sensor element 94 is acted upon by pressures which change inaccordance with the combustion process.

The conductor tracks 90, 92 or other conductor elements contacting theceramic disc 84 preferably consist of silver. In a variant of theembodiment shown in FIG. 4, the sensor element 94 could also be arrangedmore inside the opening 96, in which case this opening is then filledfrom both sides with a suitable elastomeric material so as to enabletransfer of the force and adaptation to the engine component surfaces;in this case the two plastic sheets 86 and 88 could also be dispensedwith as the ceramic disc together with the contact elements can besealed off against all media with which the cylinder head gasket comesinto contact (above all, cooling water and engine oil) with theelastomeric layers arranged on both sides of the ceramic disc 84. Ineach case, the plastic sheets and/or the elastomeric layers eliminatethe danger of an electric short circuit. The metallic contact elementscan be additionally soldered or connected to the ceramic disc 84 by anelectrically conductive adhesive.

In the embodiment illustrated in FIG. 4, the engine block or thecylinder head could form a common ground contact for the ceramic discsof all sensor elements if the top plastic sheet 86 is dispensed with andthe top conductor track 90 or a metal-coated region of the top surfaceof the ceramic disc 84 is flush with the top main surface 102 of thesealing plate 98. Above all, in this case, the sensor element could besealed against water and oil by the sealing plate 98 being provided onits top main surface 102, for example, in a screen printing process,with an elastomeric sealing bead which completely encloses the opening96.

In a preferred embodiment, the ceramic disc 84 has a round shape with adiameter of approximately 5 mm. Such piezoelectric ceramic discs arecommercially available with a thickness of approximately 0.2 mm onwards.The diameter of the ceramic disc should be as small as possible in orderthat the bending stress to which the ceramic disc is subjected will alsobe low as there will otherwise be a risk of it breaking on account ofthe brittleness of ceramic material. Also such small sensor elements canbe arranged sufficiently close to the combustion chamber orifices withany geometrical design of the cylinder head gasket. The elastomericmaterials used to imbed or support the sensor elements on one sideshould be relatively hard so that high-frequency oscillations(approximately 7 kHz in the case of knocking combustion) are detectedand a high measuring efficiency thus achieved. On the other hand, theelastomeric material should be sufficiently soft to enable adaptation tothe engine components (engine block and cylinder head). The elastomericmaterial should also be resistant to creep. Prior to assembly in thesealing plate of the cylinder head gasket, the ceramic discs areexpediently soldered or adhesively connected to a plastic sheet providedwith the conductor tracks, the sheet is then placed on the sealing platein such a way that the ceramic discs engage in the openings of thesealing plate and these openings are then filled out with theelastomeric material from the rear side.

The embodiment illustrated in FIG. 5 of a sensor element 106 which againcontains a piezoelectric ceramic disc 108 as main component isparticularly well suited for this installation variant. The two oppositemain surfaces of the ceramic disc 108 are provided with metallic contactlayers 110 and 112, the ceramic disc is received by a metallic casing114 which is open at the top and simultaneously serves as housing and asone of the two electrodes, and the interior of the casing 114 which isnot filled out by the ceramic disc 108 is filled with a suitableinsulating material 116. The sensor element 106 is attached to a plasticsheet 118 which has metallic conductor tracks 120 and 122 printed on it,with the conductor track 120 contacting the contact layer 110 and theconductor tracks 122 the metallic casing 114. Other contact elementscan, of course, also be used instead of the conductor tracks 120 and122.

Instead of the polyimide sheets mentioned hereinabove,temperature-resistant polyester sheets can also be used.

The embodiment of an inventive cylinder head gasket illustrated in FIGS.6 and 7 has an elongate sensor 130 which extends past all of thecombustion chamber orifices of the cylinder head gasket. The sensor 130is a known piezoelectric elastomer cable, but in like manner the sensorcould also be designed as a glass fiber light guide sensor, which willbe explained in further detail hereinbelow.

The cylinder head gasket 132 shown in FIG. 6 has a sealing plate 134with combustion chamber orifices 14', 16', 18' and 20' provided withcombustion chamber borders 136 as well as screw holes 26' for cylinderhead screws.

The output signals generated by the sensor 130 are picked up via lines138 and 140 and fed to a microprocessor 142 which is also fed via a line144 the incremental output signal of a rotational angle detector 146which is coupled with the crankshaft of the internal combustion engineand whose output signal represents the respective rotational angleposition of the crankshaft. An output line 148 of the microprocessor 142leads to the engine control system which is not illustrated.

FIG. 7 shows the sealing plate 134 and a combustion chamber border 136.The sealing plate 134 consists essentially of a metal carrier plate 150from which stamped-out and bent anchoring tongues 152 protrude upwardsand downwards. These serve to join to the metal carrier plate two layersof soft material 154 and 156 which are rolled onto the two sides of themetal carrier plate 150. The anchoring tongues 152 are arranged in rowsrunning parallel to the longitudinal edges 158 and 160 of the sealingplate 134. Beside a row of anchoring tongues protruding upwards from themetal carrier plate there extend two rows of anchoring tonguesprotruding downwards from the metal carrier plate (and vice-versa).

In accordance with the invention, there is stamped out of the sealingplate 134 a longitudinal slot 162 with its ends expediently notextending as far as the edge of the sealing plate 134 so as not toimpair the rigidity of the sealing plate. Inserted in this longitudinalslot is the elongate sensor 130 whose diameter is advantageouslyidentical with the thickness of the sealing plate 134. The area of thelongitudinal slot 162 which is still free is again filled out with anelastomeric material 164 in which the sensor 134 is embedded and whichalso serves to secure the sensor 130 in the longitudinal slot 162.

The sensor 130 is formed by a commercially available, piezoelectricelastomer cable which is designed in the fashion of a coaxial cable andconsists of a jacket-like, metallic outer conductor 166, a metallicinner conductor 168 forming a core and an elastomeric, piezoelectricmaterial surrounding the inner conductor 168 and filling out the outerconductor 166. At all the locations where the sensor 130 is pressed bypressures which vary with respect to time, the elastomeric,piezoelectric material generates an electric potential differencebetween inner conductor 168 and outer conductor 166 which varies withrespect to time; the electric output signal of the sensor 130 which isbased on these potential differences which vary with respect to time canbe picked up via the lines 138 and 140 which are connected at one end ofthe sensor to the outer conductor 166 and the inner conductor 168,respectively. The microprocessor 142 now has a window function fordetecting the desired useful signals individually associated with thecombustion chamber orifices 14', 16', 18' and 20' and for fading out allof the other parts of the output signal of the sensor 130; this windowfunction is controlled by the output signal of the rotational angledetector 146 in such a way that there only appear on the output line 148of the microprocessor 142 those useful signals which are generated bythe sensor 130 within rotational angle ranges of the crankshaft whichare predetermined by the window function of the microprocessor. If, forexample, misfirings are to be recognized by the sensor 130, theserotational angle ranges lie such that they contain the upper deadcenters of the pistons of the four cylinders allocated to the fourcombustion chamber orifices 14', 16', 18' and 20'. In this way it isensured that of the output signals generated by the sensor 130, onlythose parts are utilized as useful signals which can be strictly andcylinder-specifically allocated to those periods of time during thecombustion processes in the various cylinders which are of interest forthe monitoring of the engine, whereas all other parts of the outputsignals generated by the sensor 130 are faded out by the window functionof the microprocessor 142.

Therefore, in the embodiment according to FIGS. 6 and 7, the sections ofthe sensor 130 located closest to the combustion chamber orifices 14',16', 18' and 20' form the sensor elements or sensitive sensor areaswithin the meaning of the present invention.

If the sensor 130 is formed by a piezoelectric elastomer cable, it canadditionally assume the sealing function of an elastomeric sealing beadin the way in which it is otherwise often attached to the sealing plateof a cylinder head gasket; it is then merely necessary to allow thepiezoelectric elastomer cable to protrude on one or both sides beyondthe sealing plate. The same also applies to the elastomeric material 164in which the piezoelectric elastomer cable is embedded. A specialadvantage of the sensor 130 in the form of a coaxial cable is to be seenin the fact that electric interferences acting from the outside are wellshielded off by the outer conductor 166 and electric shielding from aconnection plug for the sensor is possible in a simple way. In amodification of the illustrated embodiment, it is, furthermore, possibleto provide a separate, shorter sensor for each individual combustionchamber orifice. Instead of a sensor cable, a flat sensor plate orplates can also be used--these are constructed like a capacitor with thepiezoelectric, elastomeric material replacing an insulating dielectric.

FIG. 8 shows a section of a further embodiment of an inventive cylinderhead gasket which with the exception of the type of the sensor can, inprinciple, correspond to the embodiment according to FIGS. 6 and 7. FIG.8 shows an area of a sealing plate 180 which is constructed in exactlythe same way as the sealing plate 134 of the cylinder head gasketaccording to FIGS. 6 and 7; its metal carrier plate was designated 182,the anchoring tongues protruding in one direction from the metal carrierplate are indicated in a row of such tongues at 184. In FIG. 8, however,one sees only one of the two layers of soft material, namely the layerof soft material 186 corresponding to the layer of soft material 156according to FIG. 7 as there was machined in the top layer of softmaterial of the embodiment according to FIG. 8 a groove which extendsonly as far as the metal carrier plate 182 and in which an elongatesensor 188 corresponding to the sensor 130 of the embodiment accordingto FIGS. 6 and 7 was inserted. The groove was then filled out with arelatively hard, elastomeric material 190. In accordance with theinvention, the sensor 188 is a known glass fiber light guide sensor withits transmission loss being changeable as a function of time bytime-variable bending of the light guide axis. This is a knowneffect--by deformation of the glass fiber light guide in the sense ofmicro-bendings of the light guide axis, light exits from the light guideat the bending locations, whereby the transmission loss of the lightguide is increased; therefore, if the light guide is bent to differentdegrees at certain locations as a function of time, the transmissionloss likewise changes at these locations as a function of time.

As the metal carrier plate 182 unavoidably becomes uneven when the twolayers of soft material are rolled onto it, the sensor 188 is bent todifferent degrees along its axis when it is placed on the metal carrierplate 182 and the changes in the sealing gap which occur duringoperation of the engine then result in corresponding changes in thebendings of the light guide with respect to time and hence incorresponding changes in the transmission loss with respect to time inthe areas of the sensor 188 which are relevant for the registering ofthe combustion process.

If a common glass fiber light guide sensor is used for all of thecombustion chamber orifices of the inventive cylinder head gasket, thesame applies to the processing of the signals as was stated inconnection with the embodiment according to FIGS. 6 and 7.

Finally, a section of a further embodiment of the inventive cylinderhead gasket is shown in a plan view in FIG. 9. FIG. 9 shows a sealingplate 200 with two combustion chamber orifices 14" and 16", the edgeareas of the sealing plate 200 surrounding these combustion chamberorifices again being provided with combustion chamber borders 202. Screwholes in the sealing plate 200 were designated 204.

An elongate sensor 206 is positioned on the sealing plate 200, but itcan also be embedded in the sealing plate. In this embodiment, too, thesensor 206 is again to extend past all of the combustion chamberorifices of the cylinder head gasket, i.e., it is to be common to all ofthese combustion chamber orifices. The sensor 206 is a multilayer stripof sheet, more specifically, preferably a strip of sheet with apiezoelectric, elastomeric layer or with a dielectric layer so that inthe latter case the sensor 206 is a capacitive sensor. For thecylinder-specific registering of the combustion process, there arearranged in the regions of the sensor 206 located closest to thecombustion chamber orifices at the top and bottom on the piezoelectricor dielectric layer metallic contact layers 208 which for reliableavoidance of electric short circuits are preferably substantiallynarrower than the piezoelectric or dielectric layer and from each ofwhich a conductor track 210 leads away in order to pick up a sensorsignal in each sensor area which is relevant for the cylinder-selectiveregistering of the combustion process.

As mentioned previously hereinabove, in all of the embodiments withpiezoelectric sensor elements illustrated and described herein, thesecan be replaced by piezoresistive sensor elements.

If an elongate sensor in the form of a piezoelectric strip of sheetcommon to all combustion chamber orifices is used, it is recommendableto make the sensor strip wider in the region of the sealing platebetween the screw holes than in the other regions in order to improvethe ratio of the useful signal to interference signal components.

Instead of the plug connection explained in conjunction with FIG. 1, theconnection lines leading to the sensor elements or to the sensitiveareas of the sensor could also be led away from the cylinder head gasketin the form of a cable harness in order to avoid the risk of a plugwhich is attached to the cylinder head gasket becoming released from thecylinder head gasket on account of vibrations occurring duringoperation.

In embodiments such as that of FIG. 8 in which the soft material of thesealing plate is partially removed, it is not absolutely necessary toremove the soft material as far as the metal carrier plate as a thinlayer of the soft material can readily remain on the metal carrier platewithout impairing operation of the sensor, it may even be sufficient tosimply impress a depression such as a channel in the soft material.

The elastomeric materials used to embed or cover the sensor elements ora sensor and metallic contact and/or conductor layers are expedientlyapplied in a screen printing process.

If a metal carrier plate without anchoring tongues is used, i.e., asmooth metal carrier plate, the unevennesses required for a glass fiberlight guide sensor can also be brought about with a corresponding tool,for example, during the impressing of a channel for receiving the sensorin the soft material of the sealing plate.

Special mention should also be made of the fact that the metal casing114 shown in FIG. 5 has the advantage that the ceramic disc cannot bedestroyed by slide movements occurring between cylinder head, cylinderhead gasket and engine block during operation of the engine

Finally, reference will also be made to another embodiment of a sensoror sensor element which can be used in accordance with the invention:The pressure forces generated by the sealing gap oscillationsperpendicular to the plane of the cylinder head gasket which act on thelatter and vary with respect to time can be used to change the electrictransition resistance between two superimposed, electrically conductiveelements so that these two elements form a resistive sensor elementwithin the meaning of the present invention. Such sensors are known in acompletely different field, and in this connection reference is to behad to U.S. Pat. No. 4,734,034, the disclosure of which is to constitutepart of the present application.

Regarding the recognition of knocking combustion, it should also bepointed out that with otherwise identical operating parameters (speedand torque) knocking combustion results in a clear increase in theamplitude of the signal supplied by the respective sensor element of aninventive cylinder head gasket (in comparison with normal combustionwhich does not knock). Knocking combustion does, however, also result inhigh-frequency signal components (more than 5 kHz) which arecharacteristic of the knocking and are likewise detectable in areliable, cylinder-specific manner with an inventive cylinder headgasket.

I claim:
 1. A generally rectangular, plate-like cylinder head gasket forsealing a gap between an engine block and a cylinder head of amulti-cylinder internal combustion engine having several combustionchambers, said gasket having two main surfaces, two longitudinal edgesand two lateral edges and comprising:a) a group of substantiallycircular combustion chamber orifices; b) web-like areas between saidcombustion chamber orifices, each of said web-like areas beingsubstantially symmetrical to an imaginary center plane orientedsubstantially perpendicular to said main surfaces; c) a generallyrectangular sealing plate having at least one opening defined by aninternal edge of said sealing plate and accommodating said combustionchamber orifices; d) screw holes for cylinder head screws, said screwholes being arranged approximately at said center planes and along linesextending parallel to said longitudinal edges; and e) at least onecombustion chamber sealing element surrounding and thereby defining saidcombustion chamber orifices, said combustion chamber sealing elementbeing fixed to the sealing plate at said internal edge of the sealingplate;wherein, for a cylinder-specific detection of movements of saidgap perpendicular to said main surfaces caused by pressure changeswithin the respective combustion chamber, f) said sealing plate isprovided with sensor elements associated with said combustion chamberorifices, said sensor elements being responsive to said pressurechanges; g) each of said sensor elements, with respect to the combustionchamber orifice associates with said sensor element, being arrangedradially outwardly of the combustion chamber sealing element of saidorifice; h) said sensor elements being disposed between said screwholes; and i) said sensor elements being selected from the groupconsisting of piezoelectric sensors, piezoresistive sensors, capacitivesensors and glass fiber light guide sensors with transmission losseschangeable by bending the glass fiber light guide.
 2. The gasketaccording to claim 1, wherein each of said sensor elements is disposedapproximately at one of said lines.
 3. Cylinder head gasket as definedin claim 1, wherein said sensor elements are formed by sensitive areasof an elongate sensor, said elongate sensor extending past all of saidcombustion chamber orifices and having inactive areas between saidsensitive areas.
 4. Cylinder head gasket as defined in claim 3, whereinsaid sensor elements comprise sections of an elongate glass fiber lightguide sensor extending past all of said combustion chamber orifices,wherein said sealing plate comprises a metal carrier plate coated onboth sides with soft material and provided with anchoring tonguesarranged in rows extending substantially parallel to said longitudinaledges, the tongues of adjacent rows protruding from said metal carrierplate in opposite directions and engaging in said soft material, whereinsaid glass fiber light guide sensor is disposed on one side of thecarrier plate opposite one of said rows provided on the other side ofthe carrier plate and is inserted in the soft material and is coveredwith an elastomeric substance.
 5. Cylinder head gasket as defined inclaim 1, wherein said sensor elements are selected from the groupconsisting of displacement pick-up means, force pick-up means, pressurepick-up means, and oscillation pick-up means.
 6. Cylinder head gasket asdefined in claim 1, wherein said sensor elements are located in thevicinity of said associated combustion chamber sealing element. 7.Cylinder head gasket as defined in claim 1, having two terminalcombustion chamber orifices located adjacent said two lateral edges,wherein at least one of said sensor elements is associated with one ofsaid terminal combustion chamber orifices, said at least one of saidsensor elements being arranged between the adjacent said one of saidcombustion chamber orifices and the adjacent lateral edge.
 8. Cylinderhead gasket as defined in claim 1, wherein said sealing plate includestwo main surfaces and external edge regions having a shape such that inat least one of said edge regions, at least one of the main surfaces isexposed and forms an uncovered surface area when the gasket is sealingsaid gap, and wherein said sensor elements are provided with connectionlines extending from the sensor elements to said uncovered surface area.9. Cylinder head gasket as defined in claim 8, wherein said uncoveredsurface area includes plug connection elements.
 10. Cylinder head gasketas defined in claim 1, wherein said sensor elements are covered by anouter plastic sheet.
 11. Cylinder head gasket as defined in claim 10,wherein said sensor elements are enclosed between said outer plasticsheet and an inner plastic sheet bonded to said sealing plate. 12.Cylinder head gasket as defined in one of claims 8 and 10, wherein saidconnection lines are covered by said outer plastic sheet except forconnection points.
 13. Cylinder head gasket as defined in claim 11,wherein said connection lines are conductor paths which are printed onone of said outer and inner plastic sheets.
 14. Cylinder head gasket asdefined in claim 8, wherein each of said connection lines extends in ameandering course when said gasket is viewed in plan.
 15. Cylinder headgasket as defined in claim 8, wherein said connection lines are coaxialcables.
 16. Cylinder head gasket as defined in claim 1, wherein saidsealing plate includes two main surfaces at least one of said mainsurfaces being provided by a layer of soft material, and wherein saidlayer of soft material is provided with at least one impressionreceiving said sensor elements.
 17. Cylinder head gasket as defined inclaim 1, wherein said sealing plate includes at least one stamped outopening receiving said sensor elements.
 18. Cylinder head gasket asdefined in claim 1, wherein said sensor elements are covered by asurface coating applied to the sealing plate.
 19. Cylinder head gasketas defined in claim 1, wherein said sealing plate includes two mainsurfaces and each of the sensor elements has an exposed contact pointdisposed adjacent a one of said main surfaces of said sealing plate. 20.A multi-cylinder internal combustion engine having several combustionchambers, an engine block, a cylinder head and a cylinder head gasketsealing a gap between said engine block and said cylinder head, saidgasket having two main surfaces, two longitudinal edges and two lateraledges and comprising:a) a group of substantially circular combustionchamber orifices; b) web-like areas between said combustion chamberorifices, each of said web-like areas being substantially symmetrical toan imaginary center plane oriented substantially perpendicular to saidmain surfaces; c) a generally rectangular sealing plate having at leastone opening defined by an internal edge of said sealing plate andaccommodating said combustion chamber orifices; d) screw holes forcylinder head screws, said screw holes being arranged approximately atsaid center planes and along lines extending parallel to saidlongitudinal edges; and e) at least one combustion chamber sealingelement surrounding and thereby defining said combustion chamberorifices, said combustion chamber sealing element being fixed to thesealing plate at said internal edge of the sealing plate; wherein, for acylinder-specific detection of movements of said gap perpendicular tosaid main surfaces caused by pressure changes within the respectivecombustion chamber, f) said sealing plate is provided with sensorelements associated with said combustion chamber orifices, said sensorelements being responsive to said pressure changes; g) each of saidsensor elements, with respect to the combustion chamber orificeassociated with said sensor element, being arranged radially outwardlyof the combustion chamber sealing element of said orifice; h) saidsensor elements being disposed between said screw holes; and i) saidsensor elements being selected from the group consisting ofpiezoelectric sensors, piezoresistive sensors, capacitive sensors andglass fiber light guide sensors with transmission losses changeable bybending the glass fiber light guide, said engine further comprising acircuit selected from the group consisting of a control circuit, aregulating circuit and a monitoring circuit, wherein said sensorelements are components of said circuit.
 21. The engine according toclaim 20, wherein said circuit comprises means for avoiding fuel supplyto at least one of said combustion chambers when the sensor elementassociated with said combustion chamber detects misfirings in saidcombustion chamber.
 22. The engine according to claim 20, wherein saidsensor elements are knock sensors and said circuit comprisescylinder-specific point of ignition change means controlled by saidsensor elements.
 23. The engine according to claim 20, wherein saidsealing plate includes two main surfaces and external edge regionshaving a shape such that in at least one of said edge regions at leastone of the main surfaces of the sealing plate is exposed and forms anuncovered surface area when the gasket is sealing said gap, wherein saidsensor elements are provided with connection lines extending from thesensor elements to said uncovered surface area, and wherein, apart fromsaid sensor elements, at least a further component of said circuit isarranged on said uncovered surface area.